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Subject: Re: [RESEND 2][PATCH v4] hexdump: fix for non-aligned buffers
From: "H. Mijail" <hmijail@gmail.com>
In-Reply-To: <CAMuHMdWhPn4KJhzWz-QXwLMJ_N7+8FOdKMf-wnyRwwyqGt0aOA@mail.gmail.com>
Date: Thu, 9 Jul 2015 21:08:04 +0200
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        David Howells <dhowells@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jiri Kosina <trivial@kernel.org>, Joe Perches <joe@perches.com>
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To: Geert Uytterhoeven <geert@linux-m68k.org>
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> On 09 Jul 2015, at 09:16, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> 
> On Thu, Jul 9, 2015 at 4:07 AM, Andrew Morton <akpm@linux-foundation.org> wrote:
>>> The other alternative in Documentation/unaligned-memory-access.txt is the
>>> macro get_unaligned() from asm/unaligned.h. However, using get_unaligned()
>>> would mean a much more intrusive patch, since each case of the groupsize
>>> would be changed, and anyway we would still need to check
>>> CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS to avoid penalising everyone.
>> 
>> Actually, I think using get_unaligned() would be a better solution.
>> For architectures which have CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y,
>> get_unaligned() should be fast - just one instruction.

D’oh! You’re right, of course.

>> 
>> This way we avoid having different-appearing output on different
>> architectures.
> 
> Definitely.
> 
> A less optimal get_unaligned() will just be noise in the snprintf() processing
> time.
> 

OK, so thanks Andrew and Geert for your comments. I’ll reimplement using get_unaligned.